处理XStream不支持属性、值同时出现的缺陷

最新推荐文章于 2024-06-23 14:27:05 发布

最新推荐文章于 2024-06-23 14:27:05 发布 · 531 阅读

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#C #C++ #C#

本文介绍如何通过实现Converter接口来自定义XStream处理带有属性的字段的方式，并提供了一个具体的例子，展示了如何创建并注册一个自定义的AttributeValueConveter。

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XStream在处理<Field name="value">text</Field>的情况无能为力，如果要他支持就要写一个Converter，贴上Converter程序如下：

package stream;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.converters.reflection.ObjectAccessException;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.mapper.Mapper;

/**
 * 
 * @author Zhao.Allen
 * 
 */
public class AttributeValueConveter implements Converter {

	public String textName = "value";
	private Mapper mapper;
	private List convertClass = new ArrayList();

	public AttributeValueConveter(Mapper mapper) {
		this.mapper = mapper;
	}

	public void marshal(Object obj, HierarchicalStreamWriter wt, MarshallingContext context) {
		Field[] values = obj.getClass().getDeclaredFields();
		for (int i = 0; i < values.length; i++) {
			Field value = values[i];
			String name = value.getName();
			if (name.equals(textName)) {
				continue;
			}
			try {
				if (!value.isAccessible()) {
					value.setAccessible(true);
				}
				Object v = value.get(obj);
				if (v == null) {
					continue;
				}
				if (Number.class.isAssignableFrom(v.getClass()) || v.getClass().isPrimitive()) {
					wt.addAttribute(mapper.serializedMember(obj.getClass(), name), String.valueOf(v));
				} else {
					wt.addAttribute(mapper.serializedMember(obj.getClass(), name), v.toString());
				}
			} catch (Exception e) {
				throw new ObjectAccessException("Cannot set Field " + value.getName() + obj.getClass(), e);
			}
		}
		try{
			Field field = obj.getClass().getDeclaredField(textName);
			if(!field.isAccessible()){
				field.setAccessible(true);
			}
			Object v = field.get(obj);
			if (null != v && !"".equals(v.toString())) {
				wt.setValue(v.toString());
			}
		} catch (Exception e) {
			throw new ObjectAccessException("Cannot set Field " + textName + obj.getClass(), e);
		}
	}

	public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
		Object obj = context.currentObject();
		if (obj == null) {
			try {
				obj = context.getRequiredType().newInstance();
			} catch (Exception e) {
				throw new ObjectAccessException("Cannot construct " + context.getRequiredType().getName(), e);
			}
		}

		Iterator attNames = reader.getAttributeNames();
		while (attNames.hasNext()) {
			String attName = (String) attNames.next();
			if (attName.equals(textName)) {
				continue;
			}

			try {
				Field field = obj.getClass().getDeclaredField(mapper.realMember(obj.getClass(), attName));
				if (!field.isAccessible()) {
					field.setAccessible(true);
				}
				String v = reader.getAttribute(attName);
				if (null == v || "".equals(v)) {
					continue;
				}
				Class fieldType = field.getType();
				Constructor strnum = fieldType.getDeclaredConstructor(String.class);
				field.set(obj, strnum.newInstance(v));
			} catch (Exception e) {
				e.printStackTrace();
				throw new ObjectAccessException("Cannot construct " + obj.getClass(), e);
			}
		}
		String value = reader.getValue();
		if (null != value && !"".equals(value)) {
			try {
				Field field = obj.getClass().getDeclaredField(mapper.realMember(obj.getClass(), textName));
				if (!field.isAccessible()) {
					field.setAccessible(true);
				}
				field.set(obj, value);
			} catch (Exception e) {
				e.printStackTrace();
				throw new ObjectAccessException("Cannot construct " + obj.getClass(), e);
			}
		}
		return obj;
	}

	public boolean canConvert(Class clazz) {
		/*Iterator it = convertClass.iterator();
		while (it.hasNext()) {
			Class c = (Class) it.next();
			if (c.equals(clazz)) {
				return true;
			}
		}return false;*/
		return convertClass.contains(clazz);
	}

	public Iterator getConvertClass() {
		return convertClass.iterator();
	}

	public void addConvertClass(Class cc) {
		this.convertClass.add(cc);
	}

	public String getTextName() {
		return textName;
	}
	public void setTextName(String textName) {
		this.textName = textName;
	}
}

使用方法：

XStream stream = new XStream();
stream.alias("h-cell", HCell.class);
stream.aliasAttribute(HCell.class, "width", "alias"); 
AttributeValueConveter converter = new AttributeValueConveter(stream.getMapper());  
converter.addConvertClass(PhoneNumber.class);  
stream.registerConverter(converter);
stream.registerConverter(new AttributeValueConveter(stream.getMapper()));